Makes me think that there's potential for a drone with a bulb shutter - provided the drone can remain entirely stable, the things you could do with an aerial view of a city street would be incredible...

Actually, that gives me an idea for an image, but it wouldn't be too difficult to pull off, so I'll describe it here instead :P

Not exactly controlled light painting, but a view from above, down onto a city street at about a 35 degree angle, in the early evening. A trail of smart phone screens illuminating the paths along which people have walked following their work day / event / conference whatever. Kind of like a traditional long exposure of cars along a city street, except the "vehicles" are the people's phones.

Light up a single person with rear-curtain sync flash at the end, and I think it would be a wonderful piece. Trying to think of locations in my local area where i could pull this off now... :D